V O L U M E 2 4 , NO. 11, N O V E M B E R 1 9 5 2
1713
tained before, but it indicated the nature of the original material which could then be duplicated.
Table 11. Relative Peak Heights Obtained from Analysis of Pyrolysis Products of Eight Different Alkyds d e
OTHER APPLlCATIONS
41 27 Alkyd 1 7 64 95 0 2 28 1 75 100 3 0 0 110 60 4 2 6 50 80 42 72 5 3 0 33 75 6 0 0 0 0 52 95 7 8 0 0 85 52 Peak 44 = 100 Alkyds used 1 . Short oi! (37% soybean) high phthaliq (40%) 2. Short oil (35% dehydrated castor) high phthalic (40%) 3. Long oil (73% soybean) 1?w phthalic (12%) Short oil (25%) phthalic (33%) containing oiticica oil ?. a . Castor type resin 6. Sorbitol type 7. Resin modified type 8. Phenolic modified type 105
In another field, that of the proteins, the relative amounts of bome of the amino acids are indicated by this technique. Figure 5 shows the relatively large sulfur content of albumin by the large 34 (H2S) peak, compared with pepsin which contains much less sulfur. Other differences, such as the toluene, acetic acid, and methanol peaks indicate differences in other kinds of amino acids. Spectra of decomposition products of other proteins reflect their composition also, and it may be possible to gain some knowledge of the composition of these complex materials in addition to identifying them by proper interpretation of the spectra of their pyrolysis products. Structural changes due to aging of Formvar are reflected in a comparison of the decomposition products of fresh and aged samples; and the interpretation of the spectra as to the nature of these changes agrees with other results (3)in so far as the spectra could be interpreted. \Vhile this description of results has been restricted to the mass spectrometric identification of the pyrolysis products obtained in a very specific way, other methods of analysis and other conditions of pyrolysis may be more suitable for a particular investigation. For instance, in the case of poly F-1113, some of the silicones, and presumably other materials, pyrolysis a t low temperatures, while it yields a very complex mixture, gives catalyst fragments and impurity and end group fragments which may often be of very great importance. Low temperatures also are better euited to the identification of plasticizers. Hence, the kind of analytical information desired may govern the choice of conditions. The method and conditions that were described in detail here were thought to be best for the immediate identification of the main components of any sample likely to be encountered. LOR temperature pyrolyses are more difficult, more time-consuming, and unstandardized. The mass spectrometer is the analytical tool used in this description and is probably more suited for the work than any other instrument, but the pyrolysis products can be observed in other ways. In fact, the more tractable pyrolysis products of polymeric materials that would be extremely difficult to sample directly have been examined by the infrared spectrometer, and the original so identified ( 7 ) . CONCLUSIOX
The volatile pyrolysis products of complex materials are often characteristic of the original material, and an analysis of these
97
57 56 55 70 Relative Peak Heights 8 28 100 80 45 100 90 10 22 40 45 16 18 60 56 8 38 5 10 46 35 34 6 8 12 70 55 4 20 46 42 25
decomposition products will establish the identity of the original. Using the mass spectrometer as the analytical tool, very small samples of a wide variety of complex materials can be easily and quickly identified. LITERATURE CITED
Achhammer, B. G., Reiney, M.J., Wall, L. A., and Reinhart, F. W., J . Polymer Sei., 8, 555 (1952). Barnes, R. B., Gore, R. G., Liddel, U., and Williams, V. Z., “Infrared Spectroscopy,” S e w York, Reinhold Publishing Corp., 1944. Beachell, H. C., Fotis, P., and Hucks, J., J . Polymer Sci., 7, 353 (1951).
Berl, W.G., “Physical Methods in Chemical Analysis,” p. viii, New York, Academic Press, Inc., 1950. Casey, R. S.,“Punched Cards,” New York, Reinhold Publishing Corp., 1951.
Gorman, J. G., Jones, E. J., and Hipple, J. A., ANAL.CHEM.,23, 438 (1951).
Harms, D. L., private communication; A N A L . CHEM.,in press, Liebhafsky, H. A , and Zemany, P. D., Aa.4~.CHEM.,23, 970 (1951 ).
Madorsky, S. L., and Strauss, S., I n d . Eng. Chem., 40, 848 (1948); and other papers from Sational Bureau of Standards. Marvel, C. S.,Homing, E. C., and Gilman, H., “Organic Chemistry,” Vol. I, 2nd ed., p. 754, John Wiley & Sons, 1943. O’Seal, 15, J., Jr., and Wier, T. P., Jr., ANAL.CHEM.,22, 991 (1950).
Staudinger, H., and Steinhofer, A , Ann., 517, 35 (1935). Wall. L. A,. J. Research S a t l . Bur. Standards. 41., 315 11948). ~ Zemany, P. D., ANAL.CHEM.,22, 920 (1950). Zemany, P. D., Kinslow, E. H., Poellmite, G. S., and Liebhafsky, H. -4., Ibid., 21,493 (1949). RECEIVED for review July 23, 1952.
-4ccepted September 18, 1952.
Determination of Nonmetallic Compounds in Metals H. F. BEEGHLY Division of metallurgical Research, Jones a n d Laughlin Steel Corp., Pittsburgh 7 , P a .
C
OMPOSITIOS was one of the earliest criteria of metal quality. Later metallographic techniques gained recognition for identifying the behavior of nonmetallic compounds and assumed a leading role in research on metals. More recently. x-ray and electron diffraction (36), the electron microscope (461, internal friction mcasurernents (21, 68, 29, 43-45, 70, 86,1071, and changes in electrical resistivity ( 5 0 ) have begun to play an active part in this phase of metals research. These indirect techniques are not sufficient, Then used alone, to explain many of the things that happen during production and fabrication; consequently, methods for the quantitative isolation and positive
identification of nonmetallic compounds are recpiving renewed attention in the production and heat treatment of metals. This paper consists of two sections. The first is a review of published methods for the isolation, identification, and determination of nonmetallic compounds in metals. The second is a presentation of information on nonmetallic compounds separated from steel by the ester-halogen method (6). Beyond the scope of this paper is discussion of metallography, x-ray and electron diffraction, or other techniques primarily concerned with identification of inclusions in a metal surface. A major portion of the paper deals with ferrous metals-mainly
,
1714
ANALYTICAL CHEMISTRY The known methods and reagents for isolation and identification of nonmetallic compounds from metala are considered. Published methods for the determination of oxides, nitrides, carbides, and sulfides in both ferrous and nonferrous metals are reviewed, and, in tabular form, pertinent literature references are givento the four general isolation methods-displacement, reactions with halogens, reactions with inorganic acids, and electrolysis. A resume is given of experimental data on metal-nitrogen compounds separated from carbon steels with esterhalogen reagents. Special attention is devoted to the use of methyl acetate solutions of bromine and to the influence of previous thermal treatment on recovery of these compounds.
because more published information is available on steel than on the other metals. An endeavor is made to survey the complete field. The term “nonmetallic” as used denotes any compound of one or more metals with one or more nonmetals. There are two basic problems in determining these compounds: (1)isolation and (2) identification and analysis of the isolated constituents. Table I indicates the four general methods that have been used for isolating nonmetallic compounds from metals. SPECIFIC ISOLATION METHODS
Displacement. When an aqueous solution of a salt of any metal is placed in contact with a metal above it in the electromotive series the metal, in theory, replaces the metallic constituent in the salt, leaving nonmetallic compounds undecomposed. In practice, only the more stable compounds are isolated; these are always contaminated with insoluble reaction products which make identification and analysis difficult. Table I1 lists reagents and literature references to detailed displacement procedures. Relatively simple apparatus can be used. Some means for mixing or agitating the reaction mixture is necessary; otherwise, the reaction products coat the specimen and stop the reaction before it can go to completion. Most workers have considered it necessary to maintain an inert atmoBphere during the reaction. I n some instances, the reaction vessel is cooled during the initial stages. Specific applications of displacement reactions are shown in Table 11. Until means are devised for carrying out displacement reactions without precipitation of hydrolysis products and for separating the isolated compounds from reaction products without decomposition of the less stable compounds, they are not likely to find widespread use. I n their present state of development, they are applicable only to the determination of relatively stable compounds in metals. Table I. Types of Reactions Used for Isolating Nonmetallic Cpmpounds from Metals I. Displacement (Seutral Salts) 1. Aqueous solutions 11. Halogens 1. Aqueous solutions 2. Organic solutions 3. Anhydrous elements at elevated temperatures 111. Inorganic Acids 1. Aqueous solutions 2. Anhydrous halogen acids at elevated temperatures IV. Electrolytic 1. Aqueous electrolytes Halogens. Anhydrous halogens react with iron or steel only a t elevated temperatures. In aqueous solution, they react with many metals to form the metal halide and leave nonmetallic compounds such a8 silica and alumina unattacked. Halogens are convenient to use, since the reaction products do not coat the undissolved specimen and retard the reaction; the metal halides are relatively soluble. Thus, the residues are isolated in a comparatively pure form. Hydrolysis occurs in the course of ex-
traction and hydrolysis products contaminate the residue. Also, the halogen in contact with water may react and form sufficient acid to reduce the pH of the solution to the point where some of the less stable compounds will be dissolved. To minimize this difficulty, anhydrous alcohol has been used in place of water as solvent for the halogen. More recently, anhydrous aliphatic esters have been used. Table I11 summarizes procedures and applications for halogens in the isolation of nonmetallic compounds. Aqueous solutions of bromine dissolve many metals without decomposing relatively stable compounds such as alumina and silica. The limited solubility of bromine in water limits its utility. The more stable constituents of steel such as silica, alumina, slag inclusions, and alloy carbides are the principal compounds which have been isolated Fith aqueous bromine.
Table 11.
Reagents Used for Isolation by Displacement
Metal Solvent CuClz a ueous C U C ~ ~ : Z ~ H I C I . ~ aqueous HIO, CuClz.2KCl.ZHt0, aqueous CuSO4 20% aqueous FeClr, ‘30% aqueous HgClt, aqueous HCl, aqueAlClr.GHz0 CuClr ous BiCls, 7-8%, aqueous CuClz aqueous CuClr’ 2NH4C1, aqueous 2KC1, aqueous CuClz H g U0a)z tartaric acid, aqueous H g h , alcoholic
+
++ +
+
Compounds Isolated Austenite CbC from steel AlzOa, SiOt from steel CbC, TaC, TIN, TiOz, CbzOs from steel Oxides from steel Kitrides from alloy steel AlzOs, SiOt from steel
AlzOa from AliOa from Alios from Alios from AlzOi from Ah01 from AlzO: from
A1 A1 A1 AI A1 A1 A1
Literature Reference
66)
90)
Solutions of bromine in anhydrous aliphatic esters ( 6 ) , developed originally for isolation of nitrogen compounds, can be used for isolation of the same compounds recovered with aqueous bromine. The reaction conditions can be controlled more readily. Bromine and most metal bromides are readily soluble in the ester. Hence, use of potassium bromide or other means to get sufficient bromine in contact with the metal is not necessary. In the absence of water, hydrobromic acid cannot form to react with the less stable compounds. The maximum temperature of the isolation reaction is fixed automatically by the boiling point of the ester-bromine solution. Low isolation temperatures and an inert atmosphere can be used if necessary. So far as can be determined, the ester-halogen methods are the simplest devised thus far and are the only ones for separating from steel nitrides that are not stable in the presence of aqueous acids or alkali. A problem, which these methods made it possible to recognize, was that the thermal history of the specimen must be taken into account in selecting a specimen for the isolation of nitrogen compounds. I n carbon steels, the carbon appears in the residue as elemental carbon; metal sulfides such as manganous and ferrous sulfides are decomposed; the more stable oxides such as alumina, silica, titania, and zirconia are retained in the residue, as are the more stable alloy sulfides. No attempt has been made to determine whether free manganous or free ferrous oxides can be recovered
V O L U M E 2 4 , NO. 11, N O V E M B E R 1 9 5 2
1715
studied the rates of solution of such metals as cadmium, iron, nickel, and hfetal Solvent Compounds Isolated Literature Reference cobalt in iodine. Iodine has been investigated most exCarbides from allov steels (10) AIzOj, SiOr, slag from steels tensively of all the halogens for isolation (64. 109, 113) Nitrides, oxides, alloy carbides, and sul( 6 , 62) of nonmetallic compounds from steel. fides from steel Brt methanol AlzOa from A1 (87,106) The early work was done with aqueous Brr: anhydrous + heat B e 0 from BezC (16) solutions. Complex formers were added Chlorine Clr anhydrous + heat AlzOa, Si02 from steel and cast iron t o minimize precipitation of iron salts on Clt: anhydrous + heat TiOr from Ti the isolated residue and low solution temClr, anhydrous + heat Ah01 from A1 peratures and an inert atmosphere was Iodine I t , aqueous SiOn from steel, slag and oxides from ($4, 108) used to minimize *hydrolysis. These prewrought iron L + FeIz + NH, citrate, aque- AIzOs, Si01 from steel cautions, while partially effective, do not (17, 23, 48) ous permit analysis of steel for free manganous I t + KI, aqueous .41nOs, SiOt, silicates from pig iron, cast (94) iron, and steel and ferrous oxides. I n carbon steels, carAlzO,, SiOz, alloy carbides from steel I t , alcohol, anhydrous (76, 78,79, 89,94, 96,109) It, ester, anhydrous, aliphatic Nitrides, oxides, alloy carbides, a n d sulbides, nitrides, and sulfides are decomposed (6) fides from steel into their elements. Silica, alumina, sili11, methanol Ah01from A1 (206) cates, aluminates, ferric oxide, and slaglike inclusions appear to be recovered quantitatively in the aqueous iodine residues. quantitatively. It seems likely that the ester-halogen reagents Iron carbide and sulfides of iron and manganese may be partially function better in this respect than aqueous halogens, and the recovered. Although there is little clear-cut experimental eviresidue would contain less contamination because the reaction dence, it seems probable that certain of the alloy carbides, niproducts are somewhat more soluble in the ester than in water or trides, and sulfides would appear quantitatively in the residue. alcohol. Also, there are fewer possibilities for undesirable side Phosphorus from the original metal appears in the residue in reactions between the halogen and the ester. Uses of ester varying amounts and makes the accuracy of analysis uncertain. ~olutionsof halogens for isolation of nonmetallic compounds from T o avoid hydrolysis of iron, JTillems (10 9 ) introduced the use nonferrous metals have not been described in the literature, alof iodine dissolved in absolute methanol. The isolation was though such applications appear feasible. carried out in an atmosphere of nitrogen and the temperature was The characteristic4 of the ester-halogen reagents can be modikept low with running water. Rooney and Stapleton ( 7 8 ) confied by use of iodine in place of bromine and by using longer chain structed apparatus for carrying out the entire isolation reaction esters in place of methyl acetate. and recovery of the nonmetallic compounds in a dry, inert atmosAlcoholic solutions of bromine have found only limited appliphere a t a controlled temperature. Dried iodine and absolute cation. If not used in anhydrous form, alcoholic solutions have alcohol freshly distilled from calcium were used in the proportion few advantages over aqueous solutions. Alcohol is inconvenient of 70 grams of iodine and 600 ml. of alcohol for 6 to 8 grams of to prepare and store in anhydrous form and reaction of bromine sample. The only possibility for formation of hydrolysis with alcohol during the isolation reaction is a potential source of products was by reaction of the iodine with the alcohol to form both water and hydrobromic acid. water and hydrogen iodide-a reaction which probably occurs and Anhydrous bromine a t elevated temperatures apparently has is accelerated by the presence of water. Therefore, despite the not been used for isolation of nonmetallic compounds from metals. care exercised initially, n-ater may be formed during the reaction. There appears to be no reason why it could not be utilized, proMany alloy steels, including some with nickel contents up to vided the necessary experimental conditions were established. 30%, are soluble in the iodine, Iodides of molybdenum and Anhydrous, oxygen-free chlorine is frequently used for isolation titanium are relatively insoluble in alcohol and may appear in the of nonmetallic compounds. Chlorination temperatures from residue. Phosphorus and alloy carbides interfere and prevent 300' to 700" C. have been explored. Generally, the lowest temaccurate determination of oxide contents of the residues. Apparperature that will permit the metal-halogen reaction t o occur and ently, the residues from the alcoholic iodine extraction of steel at the same time be above the volatilization temperature of the were not examined for nitrogen compounds; of the easily demetal-halogen compounds should be selected. High chlorination composed nitrides, those of aluminum, silicon, and zirconium temperatures decompose the less stable compounds. Temperamight have been present in appreciable quantities in residues from tures from 300" t o 350' are considered most satisfactory. Oxides steels containing them, as would any of the more stable nitrides. of nickel and molybdenum and titanium carbide are said to chloBoth synthetic manganous oxide and sulfide were completely rinate above or n-ithin the upper limits of this range. The chloridecomposed in the alcoholic iodine a t 65'; below 33" they apnation reaction once initiated is exothermic and control must be peared to be stable. Such solvents for iodine as acetone, triexercised or the permissible temperature will be exceeded. Use of chloroethylene, benzene, carbon disulfide, carbon tetrachloride, solid specimens helps in controlling the reaction temperature. chloroform, and ethylene bromide were found to be inferior t o Certain alloy carbides, such as those of chromium and titanium, alcohol. The alcoholic iodine method n-as found to be applicable will chlorinate but remain in the residue and, by the usual proto steels containing up to 0.6% of carbon and low in aluminum and cedures for analysis of the residue, be converted to oxides. nitrogen. During the isolation reaction, it is cwsential to exclude Chlorination procedures have found their greatest application oxygen and water vapor from the reaction vessel, t o agitate during for isolation of the more stable oxides such as silica, alumina, and the solution reaction, to maintain the temperature constant, and silicates from carbon steels. There appears to be only very to deaerate the solvent before use. meager published evidence that they are applicable to pig iron, Solutions of either iodine or bromine in methanol have been cast iron, or alloy steels. Titanium oxide has been recovered from used for separating alumina from aluminum. Slightly higher titanium metal and alumina from aluminum by chlorination; it is results were obtained with iodine. These procedures apparently probable that certain alloy steels and other metals would be have not gained widespread acceptance. amenable also. Stripping of oxide films from metals for study represents a special application of halogens. Aqueous iodine (16,17), alcoMeyer and Aulich (59) studied the reactions of liquid chlorine holic iodine (104) and bromine (56), and ester-halogen solutions with different metals. Vanadium reacted with anhydrous chloof bromine and iodine have been used for this purpose. rine a t room temperature. Van Name and Bosworth (103) T a b l e 111. Halogen Methods for Isolation of N o n m e t a l l i c C o m p o u n d s
ANALYTICAL CHEMISTRY
1716
Acids. Virtually all of the inorganic acids have been used to dissolve steel and isolate silica or alumina. Silicates were separated by Dickinson ( 2 0 ) with a 10% aqueous solution of nitric acid a t room temperature. During solution, the acid was mixed by bubbling air through it. The residue was separated from the solvent by decantation, carbonaceous material was destroyed by oxidation with potassium permanganate, and the silica and silicates were recovered by filtration. Gelatinous silicic acid was removed by digestion with sodium hydroxide. Alumina if present would also be recovered by this procedure. The apparatus for isolation of nonmetallic compounds from metals by acid solution has generally been simple, consisting of a beaker or flask with some means for agitation, The residues have been recovered by filtration and analyzed by conventional or micromethods. The acids used and references to specific procedures are in Table IV.
Table IV.
Acid Solution Methods for Isolation of Nonmetallic Compounds
Metal Solvent Nitric acid l o % , aqueous s : ::32 : : :2a , Hydrochloric acid 4 N , aqueous 1 t o 2 , aqueous 20%, aqueous 3 3 % , a ueous 33% + ( ~ c I oaqueous ~. Concentrated, aqueous Dilute aqueous Anhydrous heat Sulfuric acid 12A, aqueous 6 N . aqueous Miscellaneous Acetic acid lacial Pyridine, 15%, aqueous Mineral acids, strong, aqueous
+
Compounds Isolated
Literature Reference
AlrOa and Si02 from steel &Oa and Si02 from steel Al201, Ti02 from steel
( 3 1 , 99)
($0) (2)
AlrOa, Si02 from steel (61, 96, 100) T i c , T i N , Ti02 from steel (53) A1201 from steel (33) AlzOa from steel (69) Silicates from steel (101) AlrOa from steel (83,91) AlrOa from steel (80) AliOa from A1 (11, 39, 4 0 , 4 7 , 5 5 , 108) Oxides from steel
-41208 from steel
CorOaand Coaoifrom COO MoOa from Mo powder Alios fromsteel
(11s) (66)
(14)
Acid solution methods have been used for carbon steels and for aluminum, but are not suitable for all alloy steels. I t appears that alumina and silica are sufficiently stable so that the acid concentration is not critical. For silicates and aluminatee, the more dilute acids are required. Aqueous acids have been used for isolating the more stable carbides, nitrides, and sulfides from metals. When heated, anhydrous hydrogen chloride reacts with metals to form volatile metal chlorides in much the same manner as anhydrous halogens. This method, though applicable, apparently has not been utilized for ferrous metals; it is generallv accepted for determining alumina in aluminum. Picon (68) found that dry chlorine attacks all sulfides of titanium a t 175" and that dry hydrogen chloride attacks Ti& Ti& Ti3&, and Ti& a t 220", 200", 250°, and 315", respectively, Aqueous hydrochloric acid attacks only Ti& a t loo", hot sulfuric acid attacks Ti& rapidly, and hot concentrated nitric acid attacks all titanium sulfides; only Ti& is attacked by the cold dilute acid. Electrolysis. Efforts to isolate manganous and ferrous oxides and sulfides from carbon steel prior t o 1930 apparently were failures because it was necessary for the steel solvent to be made either too acid, resulting in decomposition of the compounds, or too near the acidity a t which iron salts hydrolyzed and precipitated. A number of workers, directing their efforts to devising a s o h tion method that would avoid these difficulties, tried electrolytic methods. The methods evolved have several characteristics in common. I n each, a solid steel specimen is made the anode in an electrolytic cell, the anode is separated from the cathode by a porous diaphragm, and an attempt is made to take the specimen into solution a t a pH and current density that will neither decompose the less stable oxides and sulfides nor permit them to become contaminated with hydrolysis products. Man-
ganous oxide was believed to decompose a t a p H of 5.0 or less. Efforts were made to carry out the solution reactions a t a p H in the range 6 to 8, Treje and Benedicks (98) used an anolyte of 5% potassium bromide plus 1% sodium citrate and a catholyte of 10% cupric sulfate. Scott (81) used magnesium iodide and Fitterer (30) found 3% ferrous sulfate plus 1% eodium chloride to be satisfactory. Klinger and Koch (48)considered all of these unsatisfactory and used an anolyte of 15% sodium citrate containing potassium bromide and potassium iodide. The catholyte was 10% cupric bromide. The pH of the electrolyte, which was continuously renewed during electrolysis, was maintained a t 7. The solid steel specimen was made the anode: electrolysis was continued for approximately 24 hours for each sample with a current of l ampere a t from 10 to 20 volts. Klinger and Koch's method Fas intended to isolate silica, alumina, ferrous and manganous oxides, and ferrous and manganous sulfides. As a check on the method they determined oxygen by the vacuum fusion and chlorine methods on the same steels used for electrolysiq. Silica and alumina values obtained by the anhydrous chlorine method and electrolysis were in good agreement. Total oxygen values obtained by vacuum fusion were Ion-er than those obtained nith the electrolytic method in a number of the steels examined. Wranglen (111) considered the factors involved in the electrolytic isolation of carbides from steel. He indicated that calculations made in support of the theory on which these electrolytic methods are based are erroneous. He recommended hydrochloric acid or ammonium chloride as the electrolyte. The validity of his arguments has not been established by experimental work. Klinger and Koch noticed that part of the carbon was isolated as iron carbide with their electrolytic method. With Houdremont and Blaschczyk, Klinger (38)studied methods for isolating carbides, Aqueous solutions of acids were found satisfactory for the most stable carbides of chromium, tungsten, vanadium, molybdenum, and titanium, but were completely ineffective for the less stable carbides. It was observed that the isolated carbides had great surface area, &.ere very reactive, and ere good adsorbents for gases. I n many instances, the isolated carbides were pyrophoric. This made it necessary to carry out the isolation, storage, and identification in an inert atmosphere. Furthermore, they observed that the chemical stability of carbides varied with the state of the carbide in the original steel-Le., with the thermal history of the specimen. Blower current density was necessary to isolate finely dispersed carbides. A current density of 0.02 to 0.03 A. per sq. cm. appeared to give best results. The temperature of the electrolyte was maintained in the range of 0' to 5". A p H in the range of 3 to 4 was found to give the best recovery of carbides. Numerous electrolytes have been tried. Table V lists some typical ones with references to procedures for their use. The most recent work indicates that use of sulfate in the electrolyte, in any form, produces low results. Interest in isolation of carbides is active a t present. Among the more recent papers have been those by Blickwede and Cohen ( 9 ) ,by Koh and Caugherty (51), by Kinzel and his associates ( 4 6 ) , and by Pemberton (67). Each has used one or more electrolytic methods, Koh also utilized bromine extraction. Additional work and publication of specific data on extraction conditions will be necessary before a sound appraisal of the status of methods for the quantitative isolation of carbides can be made. Methods for isolation of nonmetallic compounds from metals have been revien-ed. These are essentially sampling techniques. Unless the compounds can be isolated quantitatively in their original form, the analyst will not have a representative sample with which to work and the significance of his results n-ill be reduced accordingly. It is unfortunate, in many published accounts of isolation procedures, that the description of the procedure or the methods of analysis are not given with sufficient clarity and detail to enable other investigators to duplicate the work or to interpret the data in the light of never information
1717
V O L U M E 2 4 , NO. 11, N O V E M B E R 1 ’ 9 5 2 about the chemical properties and influence of thermal treatment on the compounds. Any of the isolation procedures mentioned, when used with reasonable care, will be suitable for isolating the more stable nonmetallic compounds from metals. I n many instances, recovery can be made quantitative; in others, useful semiquantitative separations can be made. Especially in the isolation of nitrides and carbides, it is essential to take into consideratlon both the composition and the thermal history of the specimen. Isolation techniques for the less stable cornpounds such as ferrous and manganous oxides and sulfides are still of questionable accuracy. Electrolytic methods have permitted a t least a partial recovery of these compounds. For easily decomposed nitrides, such as aluminum nitride, the ester-halogen I wgents are effective. Identitication and Analysis. In most procedures, compouncls are recovered from the isolation reaction products by filtration 01 by centrifuging. Chemical methods Tx-ere the first to be used for identification of the compounds isolated. The residues from the early extraction procedures were purified; usually carbonaceou. material was oxidized away with potassium permanganate and siliric acid removed b j digestion with an alkali. Then the pulitied iesidue v a s analyzed by standard methods ( I S , 3 7 , 4 l , $4, 16, 7 7 , 86, 88, 92, 97). Later, micromethods were utilized in ordei better t o accommodate the small quantities isolated (36, 49, 64). Thiq pei initted use of a smaller initial sample without decreasing the accuracy of the analysis and generally shortened the time necesqary for isolation. Unfortunately, in much of the earl). work, the procedure for recovery and purification of the isolatrd residue prior to analysis was such that any of the less stable compoundb isolated TT ere decomposed before analysis stai ted; consequently, the analyses reported are not indicative of the compounds actually isolated. Microscopic examination frequent]? IT as used in conjunction mith analysis to determine the nature of the compounds in the residue. The microscope provided qualitative information onlj , but na. convenient and revealed the size and shape of the particles; more recently, in conjunction n ith isolation of carbides and nitrides, the electron microscope has been applied (46, 52, 56).
Table
\-.
Electrolytic JIethods for Isolation of Sonmetallic Compounds
N e t a l Solrent (Electrolyte) FeS01.7Hz0, 3 7 c , S a C l . 1%
+ +
FeSOc7Iln0, 3 7 0 , SaC1, l % , + S a citrate, 0.5% MgI2 K I , 300 Citric acid, 450 g./l., g./l., HCI, 60 ml./l. S a O H , 0.1 Citric acid, 2 % , ‘V,, K I , 0.1 % Na citrate t KI. 0.1%
+
+
+
+
-
HCl citric acid KCI HCI, 7 % ZnSOd. neutral HzSOr, 4 5 FeSOd, neutral KCI, 1 S, T citric acid, 0 5 5
Compound Isolated A1203, SiO2, silicates froni steel Carbides fron. tool steels Oxides and slags from steel Carbides from alloy steels
Literature Reference (SO)
(4) ( 5 7 , 8 1 , 83) (87)
Oxides from steel
(7 )
.i!zOs, SiO,. and carbides
(8)
from steel Carbides from steel
Carbides from steel
(3) (38)
Carbides from carbon and (71-73) alloy steels HC1,0.3,0.5,1.0,and2.V HCl, 1 N , Sa&Os, 2% HC1, 2 .V, KC1, 1 T HCl, 0.1 S and 0.2 S , KCI, 1 X, NazSzOs, 0.5% HCl i SnCln.2Hz0, 1% KaF, 1 hr, citric acid H F , 2 ,V HF, 2 N , SnClz FeCls HCI, 10% FeCla 7 HCl, 1070, SnCIz. 2Hz0, 1% FeSOa. 3%. 1KaC1,1’%, citric acid, 0 . 5 % HCl Carbides from alloy steels (91 HCI, 10% Carbides from alloy steels (6f) FeCh Anolyte Catholrte KBr. 5%. Na citrate, 1% CuSOi, 10% Oxides from (9, 47, 58, 98) steel h’a citrate, l6%, KBr, 1.2% CuBrl. 10% Oxides from (38, 48) steel KL 0.1%
+
++
+
+
+ -
+
+
+
+
+
These techniques, though promising, must still be considered in the experimental stage. So far as can be determined, spectrographic methods have been neglected for analysis of nonmetallic compounds isolated from metals. Probably no other method yields so much useful information for so little effort. Quantitative methods are not necessary to detect and identify the metals in a residue in a matter of a few minutes. The effect of different wash solutions in removing certain elements and the validity of variation in extraction reagents and procedures for isolating compounds of a given metal can be checked with equal ease. Where a given thermal treatment is suspected of converting a compound of a given element from a recoverable form to a soluble form and vice versa, the spectrograph ~ 1 1 enable 1 the suspicion to be confirmed or rejected. Only a very small sample (1 gram or less) is required. The technique is especially useful in finding how different thermal treatments affect recovery of compounds of a given metal. Spectrographic methods, in common with chemical analysis, do not provide direct and positive identity of the isolated compounds. At best, they indicate how much of each element has been isolated. JVith all elements accounted for, it is possible, by use of hypothetical combinations, to calculate the amounts of various compounds that could be present. Many useful data have been compiled in this xay. Khen the metal contains not one but several potential carbide-, nitride-, oxide-, or sulfide-forming elements in very small quantities, as is the case ryith many of today’s commercial metals, the question of Ivhich metal combines with which nonmetal becomes an extremely complex one. The metals need not be present in large quantities to produce this complication; in fact, some elements, when present in alloying amounts, produce compounds n i t h different behaviors than those obtained when only amounts sufficient for deoxidation are present. X-ray diffraction provides a method for “fingerprinting” the compounds and gives direct evidence as t o what compounds are present. When a diffraction pattern can be obtained, it provides positive evidence that a given compound is present and may enable its structure to be established. TWO or more compounds can be identified eimultaneously in a mixture and only a very small amount of sample is necessary. Absence of a diffraction pattern is not conclusive evidence that a compound is not present. Usually a constituent must comprise 1 to 3% of a mixture to be detected. X-ray fluorescence and activation methods offer other possibilities for detecting and determining the small quantities of metals in the residue These methods have been utilized t o a very limited extent for this purpose thus far. Summary. The principal problem in determining nonmetallic compounds in metals is to secure an isolation method that will enable the quantitative recovery, in their original forms, of the compounds uncontaminated by products of the isolation reaction; once they are isolated, they can be analyzed by established procedures. For the more stable compounds, isolation may be effected by displacement reactions, by solution in acids or halogens, or by electrolysis. For the less stable ones, such as ferrous and manganous oxides and sulfides in steel, fully satisfactory isolation procedures have not been described. Electrolytic methods are in an active state of development for isolation of the less stable carbides. Ester-halogen reagents are of specific value in isolating such nitrogen compounds as aluminum nitride, silicon nitride, and zirconium nitride. ANALYSIS FOR METAL-NITROGEN COMPOUYDS
The analysis of steel for different specific compounds presents a problem so complex that no single isolation method can be used for all compounds nor for a given compound in all grades of steel. The folloTving pertains to nitrogen compounds in carbon steels and to data on “soluble,” “total,” and “ester-halogen” nitrogen obtained with the ester-halogen and supplementary techniques
ANALYTICAL CHEMISTRY
1718
- OC.
TEMPERATURE
TEMPERATURE
-I
-1
a
+ a
100
P b
l .
80 I-
t
z
W l J
V
eo
a n
W
n
I
I
z
z
4o
W
0
U
a
t
- OC.
Bt
20
z
z
0 750
IW
1500
1250
ZOOD
I750
TEMPERATURE TEMPERATURE
- OF.
- OC.
22%
2%
TEMPERATURE -OF. T E M P E R A T U R E - OC.
CURVE I
4m
em
SQ)
7m
em om
IOOJ
IIW
CURVE 4
1x0
1x0
J
4
100
0
k
w z
k.
.c.ae4 IW z
V
L
eo
,0048
V
a
5 P
1
z
W a I
u W a
.W32
40
8
t z
20
t z
I ‘753
TEMPERATURE - O F . T E M P E R A T U R E -OC.
TEMPERATURE
Figure 1.
- OF.
CURVE 2
I IOm
-I 12%
-
I
I
I
I500
17SO
ZOOJ
TEMPERATURE --F. TEMPERATURE
c u w E 3
TEMPERATURE
lo
- 1 22%
2500
CURVE 5
- OC.
-OF.
CURVE 6
Effect of Thermal Treatment on Recovery of Kitrogen Compounds from Steel
described previously ( 6 ) . Methyl acetate was the ester and bromine the halogen in the ester-halogen procedure. All values for each curve in Figure 1 are from different specimens cut from the same piece of the respective heats. All specimens for each curve were of the same dimensions and were held a t the indicated temperature for the same length of time and then cooled to room temperature quicltly by quenching in n-ater. Curve 1shows how thermal treatment affects recovery of nitrogen in the residue from specimens (0.25 X 0.25 X 1.25 inches) of an aluminum-killed steel held for 1 hour a t temperature. Recovery of ester-halogen nitrogen varied appreciably with temperature. All of the nitrogen was soluble in each specimen. Hence, in this steel, the soluble and total nitrogen were the same over the temperature range of the experiment; there was no insoluble nitrogen present; and the recovery of ester-halogen
nitrogen varied from a minimum of 5% to a maximum of 60% of the total. “Soluble” as used here represents the nitrogen recovered from a specimen by the micro-Kjeldahl steam distillation procedure following solution in hydrochloric acid (1 to 1). “Insoluble” nitrogen is that which is not recovered by this treatment. “Total” nitrogen is that obtained by the micro-Kjeldahl steam distillation procedure following solution in hydrochloric acid (1 to 1) and digestion with a mixture of hydrofluoric acid and hydrogen peroxide. Total nitrogen should equal the sum of the soluble and insoluble portions. Ester-halogen nitrogen, unless stated otherwise specifically, is the soluble nitrogen isolated by the ester-halogen procedure-i.e., it represents the nitrogen in all compounds isolated from a steel by the esterhalogen method that are decomposed by action of either hydrochloric acid (1 to 1) or by distillation with sodium hydroxide.
V O L U M E 2 4 , N O . 11, N O V E M B E R 1 9 5 2 Curve 2 of Figure 1 gives information for a steel containing vanadium. All specimens (0.25 X 0.25 X 1.25 inches) were held for 1 hour a t temperature. Over the temperature range shown, the soluble nitrogen varied from a maximum of 90% to a minimum of 4%, the insoluble nitrogen varied from 10 to 96%, and the ester-halogen nitrogen, as just defined, remained a t a uniformly low value of 4% of the total. Curve 3 is for a steel containing silicon. The specimens (sheet 0.035 X 0.75 X 2 inches) were held 30 minutes a t temperature. The ester-halogen nitrogen values ranged from a maximum of 73% to a minimum of 6%, depending on the temperature to which the specimen was heated. The soluble nitrogen was equal to the total nitrogen in all specimens-Le., so far as the analytical methods used would reveal, the chemical properties of the aluminum nitrogen compound (curve 1) and the silicon-nitrogen compound (curve 3 ) were the same. Neither steel contained insoluble nitrogen. Curve 4 is for a steel to which zirconium was added, The specimens (0.25 X 0.25 X 1.25 inches) were held for 1 hour a t temperature. I n this example, all of the nitrogen was soluble. Approximately 75% of the nitrogen &-as ester-halogen and the amount of both soluble and ester-halogen nitrogen was virtually the same for all specimens examined. Curve 5 is for coupons (0.035 X 0.75 X 2 inches) from a sheet containing titanium. Each was held for 30 minutes a t tempera-, ture. Approximately 5% of the total nitrogen (0.0005% nitrogen) was soluble. 9 slightly greater amount of ester-halogen nitrogen was present (20% equal to 0.0016% nitrogen). Insoluble nitrogen in these specimens was equal to 95% of the total. Keither the soluble nor the ester-halogen nitrogen varied with the temperature a t which the specimen was heated. Curve 6 is for coupons (0.035 X 0.75 X 2 inches) from molybdenum-bearing steel. All of the nitrogen is soluble. Only 6% of the nitrogen is ester-halogen. 90 insoluble nitrogen is present. Neither the soluble nor the ester-halogen nitrogen varied with the thermal treatment used. So far as is revealed by the analytical methods and thermal treatments used, the nitrogen in the molybdenum-bearing steel behaves like that in a carbon steel containing no alloying or deoxidizing elements. T o amplify the discussion of Figure 1, for the samples used, ester-halogen nitrogen, as defined, can be recovered from steels containing aluminum, silicon, and zirconium. I n the above rxamples the nitrogen is associated with these elements. This portion of the nitrogen is not distinguished from the remaining iiitrogen in these steels b j any of the standard methods for determining nitrogen prior to isolation. I n the case of the former two elements only, the amount isolated can be varied by thermal treatment for the time and within the temperature ranges shown. These changes are not detected by the standard methods of determining nitrogen in steel. All the nitrogen isolated in these cases is determined if the residue is heated with hydrochloric acid (1 to 1) on a steam bath, the solution is cooled and made alkaline, and the ammonia is removed by steam distillation Kith the micro-Kjeldahl unit. To consider the case of vanadium and titanium (curves 2 and 5) in which the ester-halogen nitrogen, as defined, is virtually zero, and in which a substantial portion of the nitrogen is in the insoluble form, this insoluble nitrogen can be detected and the temperature and time necessary a t any given temperature to cause nitrogen to appear or disappear from the vanadium treated steel can be determined in this simple case by the micro-Kjeldahl steam distillation procedure (6) without prior extraction. il blank correction Tas not made on any of the values shown in Figure 1-Le., the values shown are the sum of all the nitrogen recovered from the reagents and apparatus plus that from the specimen. On applying a blank correction of 0.0008 for vanadium and molybdenum, 0.001 for aluminum and silicon, and 0.016% for titanium, the ester-halogen nitrogen values would fall to zero. Actually, a value in the range of 0.0004 to 0.0006% is
1’219 normally obtained on high purity iron. The ester-halogen separation is not necessary because the vanadium-nitrogen compound is not decomposed by hydrochloric acid of the concentration used in the standard procedure. If the ester-halogen extraction is made, however, the vanadiumnitrogen compound will be recovered in the residue. This will be the insoluble nitrogen of the original steel and, by the definition of ester-halogen nitrogen used in this paper, there will be no ester-halogen nitrogen in the steel. The statements just made for the vanadium-nitrogen compound apply also to the titaniumnitrogen compound which, for the time and a t the temperatures used for the steel in curve 5, remains constant in amount. -4s was indicated in an earlier paper (6) when bromine is used in the esterhalogen method, insoluble nitrogen compounds containing titanium may be partially converted to a form that is decomposed by hydrochloric acid (1 to 1)and an ester-halogen value higher than the soluble value will be obtained. Finally, data such as those in Figure 1 will not be obtained for all grades of steel containing the elements indicated; nor can these data be applied to all concentration ranges of a given element in the same grade. Figure 1 is based on carbon steels comparable to open hearth grades with carbon contents in the range of 0.05 to 0.15% and manganese in the range of 0.30 to 0.75%, with only nitrogen and the desired alloying element added. K i t h the exception of aluminum, the curves in Figure 1 may be considered illustrative for such steels with up to 0.50% of the single deoxidizing or alloying element. Curve 1 is illustrative of steel with aluminum in the range used commercially to produce a “fine grain” steel-Le., 0.02 to 0.06%. With aluminum much above this range, data resembling those for the zirconium-bearing steel in curve 4 are obtained. With silicon contents much above 0,50% an insoluble silicon-nitrogen compound may occur. The composition of commercial steels is frequently more complex than the simple examples cited. Two or more deoxidizing elements may be present and, frequently, not in the same amounts. For example, aluminum may be present in steels deoxidized with silicon or vanadium. The isolated nitrogen compounds may be distinguished in some instances on the basis of their difference in resistance to acid or alkali. Table VI indicates the possibility of distinguishing the soluble nitrogen combined with aluminum from that associated with silicon or zirconium. All residues were isolated by the standard ester-halogen procedure and washed with successive portions of the indicated wash solutions (a total of approximately 150 ml. was used in each case). The residues were then dried and nitrogen was distilled from them in the usual way. The cold sodium bicarbonate wash virtually eliminated soluble nitrogen in the residue from the steel containing aluminum, while no loss occurred in the residues from the steels containing silicon or zirconium. The composition of these nitrogen compounds may be established by determining nitrogen and the metals involved in the residue, using the spectrograph and suitable micromethods. Then, using hypothetical compounds, the amounts of each which could be present may be calculated. If the compounds are present in sufficient quantity, they may be identified by x-ray
Table VI. Effect of Different Wash Solutions on Nitrogen Contents of Residues from Different Steels Residues from Steels Containing A1 Si Zr Sitrogen in Residue, %“ 0.0030 0.016 0.0080 o:oi5 0.017 0.0007 0.015 0.017 0.0015 0.011 0.017 0.0008 0.014 0.014 0.0000 0.015 0.011 0.0038 0.015 0.016 0.0016 0,009 0.012 0.015 0.015 0.017 Calculated on basis of weight of original steel sample. Wash Solution
a
1720
ANALYTICAL CHEMISTRY
diffraction techniques. As carbon is always present in the esterhalogen residue-the amount varying with the original carbon content of the steel-the nitrogen compounds may be diluted by the carbon to the point where they are not detected. Sometime$ the carbon can be removed by oxidation a t a temperature belon which the nitrogen compound decomposes. Occasionally a separation can be made on the basis of differences in density of the carbon and the nitrogen compounds. There are other instances where it is permissible to remove carbon from the sprcimen-e.g., by annealing in hydrogen-before extraction xith the ester-halogen reagents. CONCLUSIOh
There is no fixed rule that can be applied to the isolation and identification of nonmetallic compounds from metals. Thp methods must be tailored to suit the particular metal and compounds to be isolated. Both the composition of the metal matriv and its thermal history must be taken into consideration i n evaluating published data on nonmetallic compounds and in comparing results obtained with different methods. The behavior of nitrogen in a steel containing 0.10% silicon, for example, is appreciably different from that in a similar steel containing 1% silicon. If the silicon is added as an alloy containing aluminum, the behavior Kill not be the same as in an aluminum-free steel. Unfortunately, most of the published work prior to World War I1 did not take this into account. I n perhaps no other phase of research are there greater need and more opportunities for coordination and close cooperation betxeen the research chemist and the research metallurgist than in the study of nonmetallic compounds. The ultimate result of such work may ne11 be a revision of a number of metallurgical concepts. REFERENCES
Alves, 5’. F., and Barros, C. de R.. A n a i s assoc. quint., Brosil, 9, 88-91 (1950). Araki. Ituo. Tetsu-to-Hagane, 26, 14-19 (1940). Arbuaov, M. P., Dokludy A k a d . S a u k S.S.S.R., 73,83-6 (1950); 74,1085-7 (1950); Zhur. Tekh. F i t . , 19, 1119 (1950). ‘Arkharov. . . .. .. .. V.. Kvater. I. S.. and Kiselev. S.T.. Bull. acad. sci. r.R.S.S., 6, 749-56 (1947). Bandel, G., Arch. Eisenhuttenu., 11, 139-44 (1937). Beeghly, H. F., ISD.ENG.CHEM.,ANAL.ED., 14,137-40 (1942); ANAL.CHEM..21, 1513-19 (1949); 24, 1095-1100 (1952). Bihet, 0. L., 15me Congr. Cham. Ind., 1936, 257-60. Bihet, 0. L., and Willems. F., Arch. Eisenhuttenw., 11, 12530 (1937). Blickwede. D. J., and Cohen, M. J., J . Metals, 1, 578-84 (1949). Boner, J. E.. H e h . Chzm. Acta, 28, 352-61 (1945). Brook, G. B., and Waddington, A. G., J . Inst. Metals, 61, 30922 (1937). Colbeck, E. IT., Craven, S. I T , and Murray, W.,J . I r o n Steel Inst., KO,2,251-86 (1936); First Rept. Oxygen Sub-Comm., Comm. on Heterogenelty of Steel Ingots, Sect. I V , Part C, 124-38 (1937); Second Rept. Sect. VI, Part 4, 109-20 (1939); Third Rept. Sect. Is’, Part A, J . I r o n Steel Inst., So. 1, 143, 332-44 (1941); Fourth Rept. Sect. 11, 13-17 (1943). Colbeck, E. W.,Craven, S.W., and Murray, W., Second Rept., Oxygen Sub-Comm., Comm. on Heterogeneity of Steel Ingots, Sect. TI, Parts 7a and 7b, 173-8 (1939). Collee, R., Chzmie and Industrie. Special No,, 465-7 (1931). Coobs, J. H., and Koshuba, JT. J , J . Electrochem Soc., 99, 115-20 (1952). Corbett, J. A,, Analyst, 76,652-7 (1951). Cunningham, T. R., and Price, R. J., IND.ENG.CHEM.,ANAL. ED.,5,27-9 (1933). Daikhes, I. I., Melallurg, No. 12, 151 (1938); K h i m . Referat. Zhzkr., No. 6, 19 (1939). Dannohl, W., Stahl u. Eisen, 6 5 , 95-6 (1949) Dickinson, J. H. S.,J . I r o n Steel Inst., 113, 177-211 (1926). Dijkstra, L. J., Philips Research Repts., 2, 367-81 (1947); Trans. Am. Inst. M i n i n g M e t . Engrs., 185, 252-60 (1949). Dymov, A. XI., and Gorelik, S.S.,Zaoodskaya Lab., 16, 648-50 (1950). Egan, J. J., Crafts, W.,and Kinael, A. B., Trans. Am. Inst. Mining and M e t . Eng., 105,169-84 (1933). Eggertz, T,, Polytech. J . , 183, 119 (1868). Ehrenberg, Wolfgang, 2. anal. Chem., 91, 1-5 (1932).
Ai.
(26) Evans, U. R., J . Chem. Soc., 1927, 1020-40. (27) Evans, U. R., and Tomilson, R., J . Applied Chem., 2, 105-9 (1952). (28) Fast, J. D., Philips Tech. Rea., 13, 165-71 (1951). (29) Fast, J. D., and Dijkstra, L. J.. Ibid., 13, 172-9 (1951). (30) Fitterer, G. R., Sockman, B. E., Krockenberger, E. A,. Meneilly, P., Marshall, E. K., Jr., and Eckel, J. F., Bur. RIines. Rept. Invest., 3205 (1933). (31) Fogel’son, E. I., Z a w d s k a y a Lab., 6, 1276 (1937). (32) Gerke, F. K., Ibid.,3,207-10 (1934). (33) Gerke, F. K.. and Lyubomirskaya, S . V., Ibid., 5, 727-31 (1936). (34) Gerke, F. K., and Zolotareva, S . V.,Ibid.,4, 39-47 (1935). (35) Goldschmidt, H . J., J . Iron Steel Inst., 160, 345-62 (1948); 170,189-204 (1952). Greenfield, S., and Sparrow, L. E., iMetaZlurgia, 45, 263-6, 270 (1952). ,and Soler, G., Metals &. Alloys, 8, 169-172 (1937). Houdremont, E., Klinger, P., and Blaschcayk, G., Arch. Eisenhiittenw., 15, 257-70 (1941). Jander, Gerhart, and Baur. Fritz. 2. angew. Chem.. 40, 488-90 (1 927). Jander, G., and Brosse, K,, Ibid., 41,702-4 (1928). Jay, A. H., and Stevenson, R.IT., Second Rept., Oxygen SubComm., comm. on Heterogeneity of Steel Ingots, Sect. VI, 195-200 (1939). Joseph, T. L., Scott, F. IT., and Kalina, hL. H., Blast Furnace and Steel Piant, 28,975-8,1073-7 (1940). Josephsson, Ake, and Kula, Eric, J . Metals, 4, 161-5 (19521. Ke, T. S., Phys. Reo., 71, 533-546 (1947); 72, 41-6 (1947); 74, 9-15, 16-20, 914-16 (1948); J . Applied Phys., 19, 28390 (1948); Trans. Am. Inst. M i n i n g M e t . Engrs., 176, 44876 (1948). Ke, T. S., and Ross, Marc, ReL:Sci. Instruments, 20,795-9 (1949). Kinzel, A. B.. J . Metals, 4, 469-88 (1952). Kippe, K. H., and hIeyer, O., Arch. Eisenhiittenzc., 10, 93100 (1936). Klinger, Paul, and Koch, Walter, Ibid.,11, 569-82 (1938). Klinger, P., Koch, IT’., and Blaschcak, G., Tech. Mitt. K r u p p Forschungsber., 3, 255-73 (1940). Koster, TT., 2. anorg. Chem., 179,297-308 (1929); Arch. Eisenhiittenw., 2,503-22 (1928-29); 3,553-8,637-58 (1929-30). Koh, P. K., and Caugherty, Betty, J . Applied Phys., 23, 42733 (1952). Leslie, IT. C., Carroll, K. G., and Fisher, R. AI., J . Metals. 4, 204-6 (1952). Lere, N., and Gurevich, S . , Zavodskaya Lab., 9, 957-61 (1940). Leve, X, F., and Sandomirskaya. 5. S., Ibid., 14, 1043-52 (1948). Lowenstein, Hirsch, 2. anorg. allgem. Chem., 199, 48-56 (1931). Mahla, E. M., and Nielson, S . A , , Trans. A n . S O C .Metals, 43,290-314 (1951). Maurer, Ed., Klinger, P., and Fucke, H., Arch. Eisenhiittenzu. 8,391-9 (1935). RIedvedeva, G . A , . and Reniin. s’. P., K h i m . Re/erat. Zhur., No. 11,63-4 (1939). RIeyer, Julius, and ;lulich. Killi. 2. angew. Chein., 44, 21-3 (1931). RIikhailova, K,F., Zarodskalja Lab., 5, 404-7 (1936). RIotok, G. T., and Waltz. E. O., Iron Age, 136, S o . 26, 23-5 (1935). Nurach. K , X‘,, Matveev, S . I., Shuikin, S . I., and Makarouskaya, T. A , , Khim.Re/erat. Zhur., 4, S O .5, 69 (1941). Sakamura, T., and Tamaaaki. S., J . Soc. Chem. I n d . J a p a n , 42,296-7 (1939). Oberhoffer,P., and Ammanii. E., Stahl u. Eisen, 47, 1336-40 (1927). Oberhoffer, P., and Piwowarsky, E., Ibid.,42, 801-6 (1922). Pavelka, F., Laghi, A , and Zucchelli, .1.,Mikrochemie aer. Mikrochim. Acta, 31, 97-101 (1943). Pemberton, R., Analyst, 77,287-92 (1952). Picon, >I,, Compt. rend., 198, 1415-17 (1934). Podkopaev, L. K,, Zanodskaya Lab., 6 , 1053-4 (1937). Polder, D., Philips Research Repts., 1, 5 (1945). Popova, E. LI,,Zaaodskaya Lab., 11,887-93 (1945). Popova, N, RI., and Platonova, A. F., Ibid.,14, 658-81 (1948). Popova, E.&I., and Rybina, 31. F., Ibid., 13, 1421-5 (1947). Rooney, T. E., Fourth Rept. Oxygen Sub-Comm.. comm. on Heterogeneity of Steel Ingots, 43-8 (1943). Rooney, T. E., Eighth Rept., Sect. 1-1, Part 6.1, 141-38 (1939); J. I r o n Steel Inst., No. 1, 143, 344-52 (1941). Fourth Rept. Oxygen Sub-Comm., comm. on Heterogeneity of Steel Ingots, Sect. 11, Part e, 18-27 (1943). Rooney, T. E., and Jones, J. W., Ibid., 110-18 (1943). Rooney, T. E., and Sloman, H. A., Ibid., 118-21 (1943).
V O L U M E 24, N O . 11, N O V E M B E R 1 9 5 2 (78) Rooney, T. E., and Stapleton, A . G., J . Iron Steel Inst., 131, 249-64 (1935). (i9) Rooney, T. E., Stevenson, W, W.,and Raine, T., Seventh Rept. on Heterogeneity of Steel Ingots, Sect. IV, 109-24 (1937). (80) Sohliessmann, O., Arch. Eisenhiittenu,., 14, 211-16 (1940). (81) Scott, F. W., IND.ESG. CHEM.,A x ~ L ED., . 4, 121-5 (1932). (82) Shandorov, A. M., Chimie & Industrie, 25, 37 (1931). (83) Shvetsov, B. S., Matveev, M. A., and Simanov, Yu. P., Zatodskaya Lab., 9, NO.2, 219-23 (1940). (84) Silverman, L., Iron Age, 159, No. 6 , 68-153 (1947). (85) Snoek, J. L., Physica, 9, 711-33 (1941); 8, 862-4 (1942); “New Developments in Ferromagnetic Materials,” Kew York, Elsevier Publishing Co., 1947. (Sti) Speight, G. E., J . Iron Steel Inst., No. 1, 143, 371-5 (1941); Fourth Rept. Oxygen Sub-Comm., comm. on Heterogeneity of Steel Ingots, 2 7 4 2 (1943). (87) Steinhiiuser, K., Aluminium, 24,176-8 (1942). 188) Stevenson, W. W.,Second Rept. Oxygen Sub-Comm., comm. on Heterogeneity of Steel Ingots, Sect. VI, Part 7C, 179-93 (1939). (89) Stevenson, W. W., and Speight, G. E., J . Iron Steel Inst., S o . 1,143,352-8 (1941). (90) Strauss, K., Aluminum and Xonferrous Rev., 3, 29 (1937). 191) Stumper, R., Chena. Z t g . , 6 5 , 23940 (1941). (92) Styri, H. T., Trans. Am. Inst. Min. M e t . Engrs., Iron and Steel Dic., 105, 185-97 (1933); Stahl w. Eisen, 54, 374 (1934). (93) Sukhov, S. I., and Korotevskaya, B. hl., Zatodskaya Lab., 4, 1104 (1935). 194) Taylor-Austin, E., Second Rept. Oxygen Sub-Comm., Eighth Rept. Heterogeneity of Steel Ingots, Sect. VI, Part 5, 12138 (1939); Third Rept. Sect. VI, Part 8,J . Iron S t e e l Inst., KO. 1,143,358-66 (1941). (95) Taylor-Austin. E., Second Rept. Oxygen Sub-Comm., coinni.
1721 on Heterogeneity of Steel Ingots, Sect. VI, Part 6B, 159-72 (1939). (96) Thompson, J. G.. and Acken, J. S.,Bur. Standards J . Research. 9,615-23 (1932). (97) Thompson, J. G., Vacher, H. C., and Bright, H. il., Trans. -47n. Insl. Mining M e t . Engrs., Iron and Steel Div., 125, 246-91 (1937). (98) Treje, R., and Benedicks, C., J . Iron Steel Inst., S o . 2, 128, 205-36 (1933). (99) Tsinberg, S. L., Z a c o d s k a y a Lab., 3, 1129 (1934). (100) Ibid., 6,358 (1937). (101) Udovenko, Ii, V., Ibid., 8, 95 (1939). (102) Urech, P., Sulsberger, R., and Schaad, E., Chimia, 4, 233-5 (1950). (103) Van Kame, R. G., and Bosnorth, R. S., A m . J . Sci., 182,20724 (1911). (104) Vernon, W.J. H., Wormwell, F., and Xurse, T. J., J . Chem. SOC.. 1939.621-32. (105) Wasmuht, Roland, and Oberhoffei, Paul, Arch. Eisenhuttenw., 2,829-42 (1929). (106) Xerner, O., 2. anal. Chem., 121,385-98 (1941). (107) TTert, C. A,, J . Applied Phys., 20, 943-9 (1949): Trans. Am. Inst. Mining M e t . Engrs , 188, 1242-4 (1950). (108) Westcott, B. B., Eckert, F. E., and Einert, H. E., Ind. Enp. Chem.. 19.1285-8 1192i). (109) Tf-illems, Frana, Arch. Eisenhuttenw., 1, 605-8 (1927) ; Stahl u. Eisen, 48, 603-4 (1928). (110) Willenis, Franr, 2. anorg. a l l g e m Chem., 246, 46-50 (1941); Chem. Zentr., 11,377-8 (1941). (111) Wranglen, G., J . Metals, 1, 919-20 (1949). (112) Wust, F., and Kirpach, N.,Mllztt. Kaiser Wilhelm Inst. Eisenforsch. Dzisseldorj, 1, 31-8 (1920). (113) Young, R. S., and Simpson, €I. R., Afetallurgia, 45, 51 (1952). R E C E I V Efor D reiiew July 31, 1952
i c c e p t e d September 18. 1932
5th Annual Summer Symposium-Ingredients of Unknown Constitution
Morphology and Chemical Composition of Certain Components of Cotton Fiber Cell Wall VERNE W. TRIPP AND JI.IKY L. ROLLINS Southern Regional Research Laboratory, New Orleans, La.
C
OTTON lint, by reason of its economic importance, has been so extensively studied by botanists, chemists, and physicists that a great deal of general knowledge is available concerning its structure and composition. Because of the inherent complesity and variability of the cotton fiber, however, precise information on its structure and chemistry is difficult t o obtain; but without greater knowledge of the architecture of the fiber and the materials present in its various parts i t is reasonable to assume that few improvements can be made in many phases of the technology of cotton. The comprehensive studies of Balls ( 3 , 4)have laid the groundwork for many of the later investigations of cotton structure ( 1 , 10, 20). Most of these technical studies have been directed at the secondary wall of the fiber, because i t contains most of the cellulose, and for this reason is physically and economically the most important component of the fiber. Other parts of the fiber cell wall, however, also contain cellulose as well as noncellulosic materials, and certain aspects of the behavior of cotton in mechanical or chemical processing arise from the nature of these components. The layered arrangement of the n-all of the cotton fiber makes it possible, by means of mechanical beating or differential solution, to isolate some of its morphological parts in a relatively intact physical condition. This paper presents a discussion of certain of the relatively minor components of the fiber, based on observations made upon isolated specimens. The light micro-
scope with polarizing attachments \vas usedfor locating and characterizing the fiber elements; the electron microscope ma used for observation of their structural details. A limited number of qualitative and quantitative chemical analyses were also carried out on the separated parts of the fiber. MORPHOLOGICAL ORGANIZATION OF T H E COlTON FIBER
The description of fiber structure which follows is widely accepted, and is essentially that given by Flint ( 6 ) ,who has reviewed the results of numerous workers and correlated their observations. The cotton fiber is a single biological cell occurring on the seed from which i t grows in numbers exceeding 10,000, I t s length a t maturity ranges from 50 mm. down t o perhaps 10 mm., depending on varietal and environmental differences; typical diameters range from 10 to 20 microns. The primary n-all is a thin tubular membrane m-hich is t h e first part of the cell t o be formed when gronth begins from the seed coat. The cuticle, a layer of waxy substances in and on the outer surface of the primary wall, is evident, but its close physical continuity x i t h the primary ~vallmakes its differentiation difficult. After the primary wall has grown t o nearly the full length of the fiber in 15 t o 20 days, the secondary wall is deposited within i t for a period of 25 to 40 days, or until growth is interrupted. The secondary wall is apparently laid down in layers of fibrils arranged from the outside of the fiber towa,d center, and the number of layers that can be differentiated-in
